<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">It's a DOS prevention mechanism. The phones (and linux appliance servers) will drop pings that cone in over a certain threshold. It just happens that Cisco routers and switches send pings at a rate much faster than Windows, and fast enough to trigger the phones to drop some. <div><br></div><div>This is absolutely expected and has been this way for a long time.</div><div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div>-Ryan</div></span>
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<br><div><div>On Feb 4, 2010, at 5:42 PM, Matthew Linsemier wrote:</div><br class="Apple-interchange-newline"><div>
<font face="Calibri, Verdana, Helvetica, Arial"><span style="font-size:11pt">All,<br>
<br>
Today when I was troubleshooting some issues on our LAN I ran across a few very weird issues in regards to ICMP and both 7965 phones and our UCM servers. In my scenario I have a 7965 phone connected to a 3750-PS switch using the voice VLAN. When I ping the phone’s IP from either my Macbook (OSX) or Windows 7, the phone promptly responds with 0% packet loss and all is happy. However, today I tried pining that same phone from our CCM voice gateway, and for whatever reason it was dropping every 6th packet or so. I tried it from our core switch, same results. Finally, I pinged it directly from the Cisco 3750 switch and again, had the same results, packet loss. I can ping any Windows or OSX server across our network without any loss. Should the phone be dropping any packets? I remember reading once that the UCM servers had built in CSA software that may cause this type of result, but I wasn’t sure about the phones. <br>
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We don’t seem to be having anyone complaining about voice calls, and the MOS scores all look good in the NAM. I’m just a bit confused, and I would like everything on my network to be perfect!<br>
<br>
Any input would be greatly apprecaited!<br>
<br>
Matt</span></font>
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